Yea, I was referring to emissions shielding, so that when in "receive" mode there is little or no signal output from the device that can indicate its presence to a targeted jammer. On 30 November 2014 07:30:49 GMT+00:00, coderman wrote: On 11/29/14, Juan wrote: ... Excuse my ignorance, but wouldn't a shielded receiver be a useless receiver? not a bad question; you don't appreciate variable attenuation until you've used it effectively to locate an emitter or test specific boundary conditions. also note that shielding may be partial to eliminate or deflect emissions from a given direction. best regards, -- Sent from my Android device with K-9 Mail. Please excuse my brevity.